Birds Flashcards
What does anisodactyl refer to?
Finger oreintation
Endothermy i.e. the ability to maintain a high core body temperature over a broad range of ambient heat by producing at rest, what kind of heat?
endogenous heat
Birds tend to have ______ hearts than mammals (relative to body size and mass)
larger
The avian eye is large relative to the size of the head and brain. They have 3 eyelids. What are they?
How many photoreceptors are in an avian eye?
One upper, one lower & nictitating membrane
4 photoreceptors
What is grating acuity?
The smallest distance between single elements of periodical pattern that is just resolved (and is reported as cycles per degree [cpd])
What clade of bird is flightless?
PALAEOGNATHAE
What is meant by pneumatic?
Hollow, thin walled, air-filled bones; marrow cavities of long bones empty
Light but very strong
What are the two major flight muscles? What do they do?
PECTORALIS –> Contracts, wing pulled down
SUPRACORACOIDEUS –> contracts, wing pulled up
Feathers attached to the “hand” are ________ and feathers attached to the “arm” are _______
Primaries
Secondaries
Forward propulsion is caused by…
Primaries on manus (hand)
Vertical lift is caused by…
Secondaries on ulna (arm)
Reduction of drag is caused by…
Alula on digit II
Coverts on ulna
Rectrices (tail) on pygostyle
At a high speed…
there is a low angle of attack, low drag
At a low speed…
There is an increasing angle of attack, but high drag
Frictional drag is caused by…
air resistance
Induced drag is caused by…
the formation of vortices at wingtips when the air flow separated from the airfoil
How are birds morphologically adapted to minimise drag?
- Lack of external ears
- Feet tucked in
- Feathers (alula, coverts, tail)
- Wing shape
STREAMLINING
In flight, if speed is high, how will the following be affected:
Drag?
Manoeuvrability?
Lift?
Flapping rate?
High speed =
low drag
low manoeuvrability
high lift
low flapping rates
In flight, if speed is low, how will the following be affected:
Drag?
Manoeuvrability?
Lift?
Flapping rate?
Low speed =
high drag
high manoeuvrability
low lift
high flapping rates
Wing loading = ?
Wing loading - mass/wing area (g/cm^2)
Name at least 3 functions of feathers
- Flight (primaries, secondaries, tail feathers)
- Insulation (down feathers, semi-plumes, filoplume)
- Waterproofing (contour, powder down)
- Display (tail feathers, contour feathers)
- Camouflage (contour feathers)
- Eye and nostril protections (bristles)
What are the 6 commonly recognised types of feathers?
Briefly describe
- Vaned or contour: form the outer coverings of a birds body, including primaries, secondaries & tail feathers
- Down: layer of loosely structured feathers beneath contour feathers which help to trap air near the bird’s body for warmth
- Semiplume: Loose and fluffy feathers similar to down feather; provides body insulation and increases the buoyancy of water birds
- Filoplume: Small hair-like feathers with a few barbs at the tip of the shaft; they occur among the contour feathers
- Bristle: Modified, vaneless contour feathers with a few bards at the base on a small, stiff rachis. They can occur around the eyes, nostrils, and in flying insect-catching birds around the mouth, called rictal bristles
- Powder down: Feathers that grow continuously and are never moulted. The barbs at their tips constantly disintegrate into a fine talc-like, water-resistant powder. Often abundant in birds that lack preen glands
What is migration?
2 way movement between breeding and wintering areas.
In mountainous regions of the world, many species of bird exhibit altitudinal migration, ________ at higher altitudes
breeding
Name at least three challenges of migration
- Precise timing of physiological events; internal clock (circannual rhythm); External factors (day length)
- Endurance performance; storage of large amounts of fat
- Orientation/navigation
How do some birds orientate during migration?
- Magnetic Compass Orientation (eye & beak)
- Solar orientation
- Visual landmarks
- Star pattern orientation
- Multiple Orientation mechanisms
Birds are strictly ________
oviparous
All birds incubate their eggs except a small group of birds in the Megapodes family. What kind of chick development is this?
Superprecocial
What is meant by social monogamy?
One male and one female cooperate to raise a brood of young
What is meant by polygyny?
A male bird breeds with more than one female
What is meant by polyandry?
A female bird abandons her eggs to breed with several males; the incubation and parental care is left to the male
What is meant by lekking?
Cluster of males to attack females; males provide nothing but genes/sperm
In polyandry, which gender is more colourful? What is this known as?
Females are more colourful
REVERSED SEXUAL SELECTION
